please, have mercy, they beg. on the street we meet four boys. they ask if we think it's safe enough for them to go back home. they talk of tanks firing and seeing other children lose limbs. they say what they have witnessed has made them all decide to be doctors, to save the victims of war. >> and the conflict in syria may be close to reaching a whole new level. that level would be the u.s. of chemical weapons against the syrian opposition. it's been a red line for the white house, and it's a growing concern for congressional leaders. >> the longer this conflict has gone, the worse it has gotten. all of those who argued for non-intervention because of the things that might happen have now happened because we failed to intervene. and the fact is that we have now reached a point where there are weapons of mass destruction that may be used and also there is a significant question about the security of these weapons, should bashar assad fall. >> we've sat for too long on the sidelines. we're now as americans getting engaged. the need for engagement